The rusting hulk of a wrecked fishing boat pierces the sandy beach at Laysan Island. It is one of dozens of ships wrecked in the Northwestern Hawaiian Islands during the past two or three centuries.

Jan TenBruggencate  The Honolulu Advertiser

It is just one of the dozens of craft that have come to their ends on Hawai'i's leeward islands, which stretch like a vast rock and coral trap 1,200 miles from Kaua'i to Kure Atoll.

The wrecks still happen every few years. In recent decades, the victims have mainly been fishing boats, but decades and centuries past, they have been coal carriers, sail-powered whalers, military ships, tankers, pleasure craft and many more.

Many had survivors, who reported the wrecks. Many more, it is assumed, did not. There is still a lot of surveying to do, but even among those areas that have been swept for lost ships, there are mystery wrecks, said marine archaeologist Hans Van Tilburg, maritime heritage coordinator for the Pacific Islands Regional Office of the National Oceanic and Atmospheric Administration's National Marine Sanctuary Program.

It's even possible that Spanish treasure galleons filled with Mexican silver wrecked here. Spanish ships crossed from Acapulco to Manila once or twice a year from about 1565 to 1810, he said.

Van Tilburg was interviewed before Hokole'a started its voyage through the islands.

One problem in identifying old wrecks is that islands are subject to huge storms, powerful seas and occasional tsunami, and old wooden ships would have left little evidence behind.

"That's a high-energy environment," Van Tilburg said.

The rough seas, tricky currents, difficult-to-spot shoals and reefs and narrow passages are among the reasons why Hokole'a's captain, Nainoa Thompson, abandoned non-instrument navigation once passing the volcanic islands of Nihoa and Mokumanamana and entering a region with an 800-mile stretch of reefs, shoals and banks.

Before approaching any low island he pores over maritime charts and often keeps two global positioning system satellite navigation units running at once  each as a check for the other.

"It's too risky, too dangerous" to take lightly, he said.

The canoe sailed up to Lisianski Island yesterday morning, but anchored three miles from shore. Coral heads and reefs, many of which are poorly charted, surround the island. The crew dived on the reef for half an hour, then raised anchor and sailed for Pearl and Hermes Atoll, which it expected to reach this morning.

Although he said the coral and marine life are remarkable there, he opted to sail by Maro Reef entirely.

The many wrecks would appear to justify his caution.

There are wrecks that could be serious threats to the environment, like the 1957 loss on Maro Reef of the Navy oil tanker Mission San Miguel. It was not carrying a cargo of oil when it went down, but would still have had a lot of residual oil in its tanks, plus its own fuel oil and other fluids.

When the Navy tried to salvage it, there was too much oil in the water for divers to work and the salvage was abandoned. And when folks returned to the site later, the ship was gone.

"It had been high on the reef, hard aground, and then there was no trace of it any more. We assume it launched itself into the deep," Van Tilburg said. One fear is that some of its tanks are still whole, but deteriorating, and that they will ultimately fail and cause a major oil spill.

"The topic worldwide is an important one. The Navy could pump it out if it is shallow enough. It would be nice to confirm its location in case it starts leaking," he said.

The captain of the three-masted copra schooner O.M. Kellogg, which wrecked on Maro in 1915 while bound from Samoa to San Francisco, complained a month later in The Honolulu Advertiser that "I think it is always bad weather at Maro Reef."

And as Hokole'a sailed by south of the reef last week, there were dark rain squalls on Maro.

The most important known marine archaeological find in the Northwestern Hawaiian Islands is probably the 1870 wreck of the USS Saginaw at Kure Atoll, Van Tilburg said.

He and a crew of divers in August 2003 found remains from the Navy ship, including two small iron cannons, iron anchors, metal rudder fittings and copper pins that once held the major timbers together.

The Saginaw had been sent to nearby Midway to blast a channel, so a coal fueling station could be established there. The ship had been built during a period when sail power was giving way to steam. It was a hybrid: a coal-fired, steam-powered side-wheeler that carried masts and sails.

All 93 men aboard survived the wreck, and lived on Green Island, a flat sand and coral islet just inside the reef.

Five of the crew sailed a small boat for help. They made it 1,200 miles to Kaua'i, but they were extremely weak by then. Four died while landing in the rough surf. The crewmembers who remained on Kure, eating seal and albatross meat and drinking rainwater, all survived.

Van Tilburg said he would love to do more work on the wreck, including trying to find the remains of the survivors' camp to see what can be learned about how they lived.

Shipwreck survivors need to be innovative, because they often have few resources.

Survivors of the 1842 wreck of the whale ship Parker at Kure used pieces of copper from their own wreck or the previous wreck of the ship Gledstanes to make cooking utensils.

Wrecks were such a common occurrence that the crew of one rescue ship in 1886 planted trees and built two 500-gallon water tanks with a rain gutter system to aid future victims on Kure. But vandals from other ships had destroyed the improvements within a year.

Advertiser Science Writer Jan TenBruggencate is sailing as a crewmember aboard the voyaging canoe Hokole'a as it sails through the Northwestern Hawaiian Islands. His dispatches are sent back via satellite phone.